The present invention relates to a field of multiple processing systems, and more particularly, the field of moving unique data in such systems without causing errors.
In many fault tolerant computer systems, there are duplicate sets of elements for carrying on the same processes as other sets of elements. The purpose of such duplication is to ensure that an error is detected if the two sets of elements produce different results. To determine whether different results are produced, there must be some mechanism for comparing the data transferred throughout the different systems.
There are occasions, however, where each set of elements will produce unique information. For example, if one set of elements detects a correctable error, it is unlikely that the other sets of elements will contain that same error. Once the set of elements with unique data tries to transfer that unique data, however, an error will be caused because unique processing systems will no longer be reaching the same results.
Therefore, it is desirable in such duplicate systems to be able to transfer unique data without causing errors.
It is also desirable, when such duplicate systems are themselves part of an additional duplicate processing system, to ensure that the data can be made globally available without disrupting the entire computer system.